We have continued to study the hereditary Waardenburg syndrome, which in its varying expression includes a hearing impairment. Members of the international Waardenburg Syndrome Consortium have found that mutation of the gene PAX3 on human chromosome 2 can cause the Waardenburg syndrome. We have shown that close to the PAX3 gene sits a highly informative CA dinucleotide repeat which now is used in genetic linkage studies of Waardenburg syndrome families. We have just began a study to characterize genes that cause nonsyndromic hereditary hearing impairment. We are continuing our study of the Bronx Waltzer mouse strain to characterize the gene, by, which underlies the deafness of this mouse. This mouse strain could be a useful model for certain kinds of hereditary deafness in Man. We have continued to study a mouse with a transgenic insertional mutation that has caused an inner ear disorder. We have found that these mice have a thin vascular stria that lacks melanin pigments and that outer auditory sensory cells are degenerated. These mice turn deaf at the age of about one month and have no skin pigmentation. These mice should become valuable as models for certain types of hereditary hearing impairment in humans. We have constructed a CDNA library based on the MRNAS from the auditory sensory organ. Such a library provides the best means for finding genes that are of specific importance for the development and function of the auditory sensory organ in health and in disease. We have initiated a study to analyze how auditory sensory cells in the chick cochlea are regenerated after damage, expecting that a full understanding of this process may be useful for possible future treatment of damaged hearing in Man.